Improvement in lifting-jacks



UNITED STATES PATENT OFFICE.

LUTHER SMITH, OF ROCHESTER, MINNESOTA.

IMPROVEMENT IN LlFTlNG-JACKS.

Specification forming part of Letters Patent N0. 56,1 l l, dated July 3, 1866.

.To all whom it may concern:

Be it known that I, LUTHER SMITH, of Rochester, in the county of Olmsted and State of Minnesota, have invented a new and useful Improvement in Lifting-Jacks and Ido hereby declare that the following is a full, clear, and exact description of the same, reference bein g had to the annexed drawings, made part of this specication, in Which- Figure l is an elevation, showing the front of the lifting-jack; and Fig. 2 is a vertical section on the line :c w, Fig. l.

The same letters refer to identical parts.

A is the stock, which has the chamber C running about one-half of its length, open to the front, and thence upward through the center of the stock A to receive the jack-bar B7 which has guides along its rear side, as shown, iitting into corresponding wings to the chamber G. This bar B is notched on its front side, as shown, to receive the point of the 1ever`D, which moves up and down upon a fulcrum formed by a stirrup, E, which is hinged to the stock at F T, and depending supports the lever D at a point as near the stock A as will permit the action of the lever.

The catch G is placed in a chamber on the front of the stock, and has a stem, around which a coiled wire spring, G", is placed, which rests against the front of the chamber at one extremity and at the other against the shoulder of the catch. This catch is square on top and beveled on the lower side to correspond with the shape of the notches in the bar. It is as wide as the notches on the bar.

The lever is also beveled on its lower edge at its posterior extremity, where it 4comes into connection with thebar, so as to make apoint for its insertion without interfering with the tooth below, the handle being elevated and the lever placed under one of the notches in the bar. It is then depressed, and the bar being forced upward, the inclined portion of the tooth resting against the corresponding portion of the catch, the catch will be forced back, the spiral spring' yielding to the pressure until, the tooth being raised beyond the catch, it is released, and immediately the spring throws it back, thus preventing the descent of the bar when the lever is released.

Having thus fully explained the character of my improvements, what I claim as my invention, and seek t0 secure by Letters Patent,

l. The catch G, actuated by the spiralspring G', in combination with the jack-bar B.

2. The arrangement of a lifting-jack having the stock A, bar B, lever D, stirrup E, catch G, and spiral spring G', the parts being constructed and'combined substantially as and for the purpose set forth.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

LUTHER SMITH.

Witnesses WALTER S. BOOTH, J. A. LEONARD. 

